Explanation of a reference dimension

Explanation of a reference dimension

• A. Primary dimension
• B. Reference dimension explanation
• C. Tolerance note
• D. Datum

Answer: (B)

A reference dimension is shown on a drawing for information only and does not govern size, tolerance, or the measurement frame. It’s there to help understand the part, not to drive manufacturing or inspection decisions. That’s why the choice labeled as a reference dimension explanation is the best fit—it directly points to the idea of conveying information about a reference dimension rather than controlling the part. The other options describe concepts that do affect manufacture or inspection: a primary dimension controls size; a tolerance note specifies allowable variation; a datum defines the measurement reference frame.

A reference dimension is shown on a drawing for information only and does not govern size, tolerance, or the measurement frame. It’s there to help understand the part, not to drive manufacturing or inspection decisions.

That’s why the choice labeled as a reference dimension explanation is the best fit—it directly points to the idea of conveying information about a reference dimension rather than controlling the part. The other options describe concepts that do affect manufacture or inspection: a primary dimension controls size; a tolerance note specifies allowable variation; a datum defines the measurement reference frame.